1. Field of Technology
The present invention generally relates to an apparatus for inspecting transparent containers such as, for example, transparent ampoules.
2. Description of the Prior Art
Hitherto, the presence or absence of foreign matter afloat or settling in a liquid medium filled in each ampoule or the like, or that of cracking in the wall forming each ampoule or the like, is automatically detected by analyzing rays of light propagating towards and reflected from the ampoule or the like. However, when it comes to the detection of the presence or absence of flaws in the outwardly tapering throat of each ampoule, automatic detection has not yet been employed and an inspector is used to perform a visual inspection.
The flaws which would generally be found in each ampoule and of which detection has not yet been automated include a bending of the ampoule throat laterally from the longitudinal axis of the ampoule, a filament-like bleeder left unremoved at the closed tip of the ampoule throat, a variation in wall thickness of the ampoule throat, undesirable adherence of foreign matter to one or both of the inner and outer surfaces of the ampoule throat, and so on.
Currently, a method has generally been practiced to detect an abnormal change in a waveform of a video signal supplied from a video camera. However, when it comes to a transparent or substantially transparent container, it is difficult to discriminate between the background light and the light which has been transmitted through the transparent container or which has been reflected from the wall forming the container and, moreover, where the throat is slightly bent relative to the body, the determination of whether the container being inspected is acceptable or whether it is defective and is, hence, to be rejected, in reliance on the image processing technique is not easy because the coverage of inspection varies with the rotation of the container being inspected unless use is made of a complicated and expensive machine system.